driveshaft help question

I pulled my driveshaft out of my '74 Mav. and found the end that goes in the back of the tranny is wore in the seal area. I have another driveshaft out of a '70(I think) but the yoke on the '70 is about 2 inches longer than the one on my '74. but the splines don't start intil 2 1/2 inches from the end inside the tube. I've attached a rough drawing of the shafts to help explain what I have. My question is: can I use the '70 shaft in my '74? Both cars are auto's and the tranny in my '74 is out of a '67 Mustang. Is there anything inside the tranny that the shaft will hit? Thanks Russ

 

Russ I am pretty sure it will be ok........but if you are worried about it might I suggest using a chop saw and cutting the excess off....right in front of the splines...

 

What about the rubber balancer/dampner? The 74 has one the 70 doesn't Is it really needed? Thanks. Russ

 

I'm not sure why they have those balancers but they are not needed if the drive shaft didnt come with it in the first place. If the drive shaft slides in the transmission far enough to get the rear universal seated without any force, then it will work just fine. Its been my experience that all 2 drs used the same driveshaft length wether it was a 6, 8, auto or manual.

 

When we still had my brother's Mav I changed the U-Joints, and the driveshaft didn't have the balancer, and when I took the tranny out of my Mav it had the balancer. The only difference between the two cars was that mine was a V8, and his was a six. They were both 73 2-doors with autos.
-Corbin

 

I tried the new shaft tonight and it would not go on the rear with the shaft in the back of the tranny The only reason I can think of is that the tranny is out of 67 Mustang. OH well It looks I'll have to take it to work and machine a little off the end. Thanks for the replies. Russ

 

Russ:

If your transmission is from a '67 Mustang, then it probably isn't a C4 Tranny.

Might be an FMX transmission. Could be longer?

(When I put my 289 motor and FMX--originally from a '67 Mustang--into my Grabber, it had already been fitted to a '71 Comet. I used the driveshaft that was on that car, just to be safe).

 

I had 2 67 Mustang covertables and they were both c4. Maby the fmx was an opion

 

67/68 Mustang automatics never came with a FMX trans. The big blocks had a C6 & the others had a C4. The FMX didn't come out until 1969.

 

Doug it is a C4. I'm going to cut the yoke at work on Friday to take ccare of it. Thanks. Russ

 

Got the yoke shortened, it looks like it has about 1 3/4 " spline engagement. Does that sound about right? Now all I have to do is get that tranny rebuilt and I should be good to go. Russ

 

Glad to see you got it all to work for you, Russ.

That's interesting about my FMX tranny. I really must have had a mut for a parts car:

A 1971 Comet with a 1967-289 motor, a 1969(?) FMX transmission, with 1977 Granada mags!

All three components are now on my 1972 Maverick Grabber!